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An important goal of grid computing is to apply the rapidly expanding power of distributed computing resources to large-scale multidisciplinary scientific problem solving. Developing a usable computational grid for Virginia Tech is desirable from many perspectives. It leverages distinctive strengths of the university, can help meet the research computing needs of users with the highest demands, and will generate many challenging computer science research questions. By deploying a campus-wide grid and demonstrating its e#ectiveness for real applications, the Grid Computing Research Group hopes to gain valuable experience and contribute to the grid computing community. This report describes the needs and advantages which characterize the Virginia Tech context with respect to grid computing, and summarizes several current research projects which will meet those needs.

This paper describes the computational methodologies of two problem solving environments (PSEs) for wireless network design and analysis, one academic (S^4 W) and one commercial (SitePlanner). The PSEs address differently common computational issues such as environment specification, propagation modeling, channel performance prediction, system design optimization, and data management. The intended uses, interfaces, and capabilities of the two PSEs are compared and contrasted in a common framework. An important future direction, for these two and all future wireless system design PSEs, is resolving the fundamental impedance mismatch between physical channel modeling and upper level protocol modeling in wireless networks.

This research proposes a language independent intra-process framework for object based composition of unmodified code modules. Intuitively, the two major programming models- threads and processes- can be considered as extremes along a sharing axis. Multiple threads through a process share all global state, whereas instances of a process (or independent processes) share no global state. Weaves provide the generalized framework that allows arbitrary (selective) sharing of state between multiple control flows through a process. In the Weaves framework a single process has the same level of complexity as a workstation, with independent “sub-processes”, state sharing and scheduling, all of which is achieved without requiring any modification to existing code bases. Furthermore, the framework allows dynamic instantiation of code modules and control flows through them. In effect, weaves create intra-process modules (similar to objects in OOP) from code written in any language. Applications can be built by instantiating Weaves to form Tapestries of dynamically interacting code. The Weaves paradigm allows objects to be arbitrarily shared – it is a true superset of both processes as well as threads, with code

Scientific codes are increasingly being used in compositional settings, especially problem solving environments (PSEs). Typical compositional modeling frameworks require significant buy-in, in the form of commitment to a particular style of programming (e.g., distributed object components). While this solution is feasible for newer generations of component-based scientific codes, large legacy code bases present a veritable software engineering nightmare. We introduce Weaves – a novel framework that enables modeling, composition, direct code execution, performance characterization, adaptation, and control of unmodified high performance scientific codes. Weaves is an efficient generalized framework for parallel compositional modeling that is a proper superset of the threads and processes models of programming. In this paper, our focus is on the transparent code execution interface enabled by Weaves. We identify design constraints, their impact on implementation alternatives, configuration scenarios, and present results from a prototype implementation on Intel x86 architectures. 1

this report together with associated papers in a Grid Computing book [32]. We can define a Grid Computing Environment as a set of tools and technologies that allow users "easy" access to Grid resources and applications. Often it takes the form of a Web portal that provides the user interface to a multi-tier Grid application development stack, but it may also be as simple as a Grid Shell that allows a user access to and control over Grid resources in the same way a conventional shell allows the user access to the file system and process space of a regular operating system

The life of a cell is governed by the physicochemical properties of a complex network of interacting macromolecules (primarily genes and proteins). Hence, a full scientific understanding of and rational engineering approach to cell physiology require accurate mathematical models of the spatial and temporal dynamics of these macromolecular assemblies, especially the networks involved in integrating signals and regulating cellular responses. The Virginia Tech Consortium is involved in three specific goals of DARPA's computational biology program (Bio-COMP): to create effective software tools for modeling gene-proteinmetabolite networks, to employ these tools in creating a new generation of realistic models, and to test and refine these models by well-conceived experimental studies. The special emphasis of this group is to understand the mechanisms of cell cycle control in eukaryotes (yeast cells and frog eggs). The software tools developed at Virginia Tech are designed to meet general requirements of modeling regulatory networks and are collected in a problem-solving environment called JigCell.